A heat wave is scorching the Southeast this Memorial Day weekend

(CNN) - Memorial Day may be the informal start of summer, but Mother Nature is going to make it feel official across nearly a dozen states this holiday weekend.

Temperatures are expected to surpass record highs around the southeastern US as a high pressure ridge brings cloudless, sunny skies and prevents thunderstorm development.

New records could be set for high temperatures in several dozen cities, from Louisiana to Virginia, setting the stage for potentially deadly conditions. Anyone who spends time outdoors this weekend should keep hydrated, wear light-colored and loose-fitting clothing, and try to stay in the shade.

August-like heat arrives in May

Several cities could see triple-digit temperatures. They include Columbia, South Carolina; Augusta, Georgia; and Tallahassee, Florida. Macon, Georgia, is expected to reach 100 degrees on Memorial Day, which would break its record high for May.

Monthly record highs could also fall in cities including Nashville; Charlotte, North Carolina; and Montgomery, Alabama. New Orleans is forecast this weekend to reach 92 degrees -- the average high there in early August.

On Memorial Day, Atlanta is expected to reach 98 degrees, which also would mark an all-time May record. The Georgia capital has only recorded nine days with temperatures of 95 degrees or greater during the month; next week could add five days to that tally, which reflects 140 years of record-keeping.

While the East sweats, the West shivers

As the eastern half of the country bakes this weekend, the western half will feel more like early spring.

After one of its latest heavy snows on record, Denver's temperatures will finally climb back to average.

But farther west, temperatures will remain far below average.

Cities such as Las Vegas; Phoenix; Reno, Nevada; and Fresno, California will be 20 to 25 degrees below normal. Las Vegas is expected to have a high temperature Sunday and Monday of only 70 degrees, which is its average for March 15.

Phoenix is expected to have a high temperature of 79 degrees on Memorial Day, its average high for March 25.